1. Field of the Invention
This invention pertains to fuel systems for internal combustion engines, and more particularly to apparatus that stores fuel for engine-driven welding machines.
2. Description of the Prior Art
Engine-driven welding machines invariably include a large tank that holds fuel for the machine internal combustion engine. The fuel tank is often flat and is preferably located in a base in the lowermost part of the machine. To make the fuel tank easy to fill, it normally includes a long filler tube that upstands from the tank top wall. The upper end of the filler tube is provided with a removable cap.
The operator of an engine-driven welding machine encounters two related problems in conjunction with supplying fuel to the machine. First, the welding machines are often transported on trucks, and the machine fuel tanks are commonly filled at truck stops. The operator usually wants to fill the fuel tank as full as possible. It is highly important that the air in the tank be vented to the atmosphere as the tank is being filled. During filling, the fuel displaces air in the tank up the filler tube. For optimum venting, the tank should not be completely full. However, the operator often fills the tank until he sees fuel in the filler tube. At that point, there is little, if any, void space in the tank. During welding machine operation when fuel is being consumed, its level falls within the tank. Ideally, the volume of fuel consumed is replaced with air from the atmosphere that descends through the filler tube.
The related problem is caused by the expansion of the fuel and any unvented fuel vapor in the welding machine tank. Fuel that comes from underground storage tanks is usually cooler than fuel at ambient temperature. The fuel and any trapped vapor in the tank therefore expands as the truck is driven to the job site. Even if the operator leaves some space in the tank filler tube at fueling, the trapped vapor expands and forces fuel up the filler tube.
It is possible that the welding machine is tilted at an angle relative to gravity during operation, such as if the truck is parked on a slight incline at the job site, with the filler tube being on the low side of the tank. The combination of the angle of tilt and the amount of fuel in the tank can result in the intersection of the tank top wall and the filler tube being below the fuel level, and a void space being created at the high side of the tank. Fuel vapors in the void space can heat and expand during welding machine operation. The vapor pressure in the void space can force fuel up and out the filler tube, which is highly undesirable.
Whether by manually topping off the tank or through thermal expansion, fuel in the filler tube of an improperly vented fuel tank is likely to slosh up the filler tube. Accordingly, fuel is spilled and runs down the welding machine as well as the truck.